Switch ContentSettingsObserver to be a RenderFrameObserver instead of a RenderViewObserver

content/browser/frame_host/render_frame_host_delegate.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_HOST_DELEGATE_H_
 #define CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_HOST_DELEGATE_H_
 
 #include "content/common/content_export.h"
 
 namespace IPC {
 class Message;
 }
 
 namespace content {
 class RenderFrameHost;
+class WebContents;
 
 // An interface implemented by an object interested in knowing about the state
 // of the RenderFrameHost.
 class CONTENT_EXPORT RenderFrameHostDelegate {
  public:
   // This is used to give the delegate a chance to filter IPC messages.
   virtual bool OnMessageReceived(RenderFrameHost* render_frame_host,
                                  const IPC::Message& message);
 
   // Informs the delegate whenever a RenderFrameHost is created.
   virtual void RenderFrameCreated(RenderFrameHost* render_frame_host) {}
 
   // Informs the delegate whenever a RenderFrameHost is deleted.
   virtual void RenderFrameDeleted(RenderFrameHost* render_frame_host) {}
 
+  // Return this object cast to a WebContents, if it is one. If the object is
+  // not a WebContents, returns NULL.

[nasko, 2013/12/16 19:47:37]

RenderViewHostDelegate has(had?) identical method that was marked deprecated and
not to be used. Should we be adding this if we wanted to remove the other such
method?

[jam, 2013/12/16 20:26:48]

I had added that comment, but afterwards realized that it's not possible to
remove.

As for this method, I had started a discussion about this on site-isolation's
mailing list but it turned private between ajwong and me at the end; where he
saw that it was necessary to have this method. The reason is that we can
sometimes be on a non-UI thread with only a render_frame and render_process IDs,
and we need to get to a WebContents. as in this change. In that case, there's no
other way to get to WC except through the RF's delegate

+  virtual WebContents* GetAsWebContents();
+
  protected:
   virtual ~RenderFrameHostDelegate() {}
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_FRAME_HOST_RENDER_FRAME_HOST_DELEGATE_H_